Testing Proton Craniospinal Radiation Therapy Versus the Usual Radiation Therapy for Leptomeningeal Metastasis, RADIATE-LM Trial

PRIMARY OBJECTIVE: I. To compare overall survival (OS) between proton craniospinal irradiation (pCSI) and involved-field radiotherapy (IFRT) in patients with breast cancer or non-small cell lung cancer (NSCLC) leptomeningeal metastasis. SECONDARY OBJECTIVES: I. To compare central nervous system progression-free survival (CNS PFS) between pCSI and IFRT in patients with breast cancer or NSCLC leptomeningeal metastasis. II. To compare time to CNS progression between pCSI and IFRT in patients with breast cancer or NSCLC leptomeningeal metastasis. III. To compare CNS PFS between pCSI and IFRT in patients with breast cancer or NSCLC leptomeningeal metastasis, as evaluated by central review of imaging. IV. To compare the rate of radiation-induced central nervous system necrosis between pCSI versus (vs.) IFRT in patients with breast cancer or NSCLC leptomeningeal metastasis. V. To characterize treatment-related adverse events using Common Terminology Criteria for Adverse Events (CTCAE) version (v) 5.0. VI. To compare patient-reported outcomes (symptoms severity subscale per MD Anderson Symptom Inventory for Brain Tumors \[MDASI-BT\] and MD Anderson Symptom Inventory for Spine Tumors \[MDASI-SP\]) in patients with breast cancer or non-small cell lung cancer leptomeningeal metastasis. EXPLORATORY OBJECTIVE: I. To compare patient-reported outcomes (symptoms interference, brain tumor-specific, spine tumor-specific subscales per MDASI-BT and MDASI-SP) in patients with breast cancer or non-small cell lung cancer leptomeningeal metastasis. OUTLINE: Patients are randomized to 1 of 2 arms. ARM 1: Patients undergo involved-field radiation therapy delivered to specific areas of LM that are causing and/or may cause symptoms 5 days a week for a total of 10 days of treatment in the absence of disease progression or unacceptable toxicity. Patients undergo computed tomography (CT) or positron emission tomography (PET)/CT during screening and magnetic resonance imaging (MRI) as well as possible lumbar puncture (LP) throughout the study. Patients may optionally undergo research blood sample and CSF collection throughout the study. ARM 2: Patients undergo pCSI radiation therapy delivered to the entire space containing the CSF, brain, and spinal cord 5 days a week for a total of 10 days of treatment in the absence of disease progression or unacceptable toxicity. Patients undergo CT or PET/CT during screening and MRI as well as possible LP throughout the study. Patients may optionally undergo research blood sample and CSF collection throughout the study. After completion of study treatment, patients are followed every 3 months for 12 months, and then every 6 months for up to 3 years from end of RT.